BACKGROUND
[0001] The present invention relates to a motorcycle including an exhaust system connected
to an engine.
[0002] In an exhaust system of a motorcycle, a plurality of exhaust pipes connected to an
engine are often collected together for connection to a single muffler. For example,
Patent Document 1 adopts a structure in which four exhaust pipes connected to the
front wall of a cylinder head are extended downward from the front wall and bent rearward
so as to pass through a portion below an engine, and in the portion below the engine,
the respective exhaust pipes are moved toward the side where a muffler is arranged
and are collected together at a collecting portion, and the muffler is connected to
the collecting portion.
[0003] When adopting a structure in which the respective exhaust pipes are collected together
to the side where the muffler is arranged as in the above-mentioned exhaust system
according to the related art, the exhaust pipes, the collecting portion, and the muffler
are concentrated on one side in the vehicle width direction, which may impair the
weight balance with respect to the vehicle width direction.
[0004] The present invention seeks to provide a motorcycle which makes it possible to achieve
a good weight balance with respect to the vehicle width direction when a plurality
of exhaust pipes are collected together and connected to a single muffler.
[0005] US2002/0050415 discloses an exhaust system for a multi-cylinder engine comprising a valve mechanism
which is arranged to provide pulsation of the exhaust gas.
SUMMARY
[0006] The invention is defined in the claims.
[0007] An embodiment of the invention provides a motorcycle including a body frame, an engine
mounted to the body frame, and an exhaust system connected to the engine, in which:
the exhaust system includes a plurality of exhaust pipes connected to a front wall
of the engine and extending rearward while passing below the engine, a collecting
portion where the plurality of exhaust pipes are collected together, and a muffler
connected to the collecting portion; and as seen from the front of the vehicle, the
plurality of exhaust pipes extend from the front wall of the engine rearward on one
side in a vehicle width direction and so as to pass below the engine, and are connected
to the collecting portion, and the muffler is arranged on the other side in the vehicle
width direction and connected to the collecting portion.
[0008] In an embodiment of a motorcycle according to the present invention, the plurality
of exhaust pipes connected to the front wall of the engine are extended from the front
wall rearward on one side in the vehicle width direction and below the engine and
are connected to the collecting portion, and the collecting portion is connected to
the muffler arranged on the other side in the vehicle width direction. Accordingly,
when seen as a whole, the respective exhaust pipes are positioned so as to be displaced
to one side in the vehicle width direction. On the other hand, the muffler is positioned
so as to be displaced to the other side in the vehicle width direction. The plurality
of exhaust pipes and the muffler that are heavy-weight objects can be thus arranged
in good balance on one side and on the other side in the vehicle width direction.
[0009] Further, when the exhaust system is seen as a whole, the plurality of exhaust pipes
are positioned on one side in the vehicle width direction, and the muffler is positioned
on the other side. This gives an element of flow and motion to the design of the exhaust
system, thereby making it possible to achieve enhanced marketability in appearance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] An embodiment of the present invention will now be described, by way of example,
with reference to the attached drawings.
FIG. 1 is a side view of a motorcycle including an exhaust system according to an
embodiment of the present invention.
FIG. 2 is a side view of the exhaust system.
FIG. 3 is a plan view of the exhaust system.
FIG. 4 is a front view of exhaust pipes of the exhaust system.
FIG. 5 is a front view of the exhaust system.
FIG. 6 is a side view of exhaust pipes of the exhaust system.
FIG. 7 is a plan view of exhaust pipes and collecting portions of the exhaust system.
FIG. 8 is a view of the exhaust pipes as seen in a cross-section taken along the vehicle
width direction (cross-sectional view taken along the line VIIIa-VIIIa, VIIIb-VIIIb
of FIG. 4).
FIG. 9 is a cross-sectional view of the collecting portion (cross-sectional view taking
along the line IX-IX of FIG. 2).
FIG. 10 is a cross-sectional view of the collecting portion (cross-sectional view
taking along the line X-X of FIG. 2).
FIG. 11 is a cross-sectional view of an oxygen concentration sensor arranged in the
collecting portion (cross-sectional view taking along the line XI-XI of FIG. 7).
DESCRIPTION OF EMBODIMENTS
[0011] FIGs . 1 to 11 are views illustrating an exhaust system of a motorcycle according
to an embodiment of the present invention. Herein, the terms front and rear as used
in this embodiment means the front and rear as viewed by the rider seated on the seat,
and the terms left and right means the left and right as viewed from the front of
the vehicle.
[0012] In the drawings, reference numeral 1 denotes a motorcycle. The motorcycle 1 includes
a double-cradle type body frame 2, an engine 3 mounted inside the cradle of the body
frame 2, and an intake system 4 and an exhaust system 5 that are connected to the
engine 3.
[0013] A front fork 7 is supported by a head pipe 6 arranged at the front end of the body
frame 2 so as to be steerable to the left and right. A front wheel 8 and a steering
handlebar 9 are respectively arranged at the lower and upper end portions of the front
fork 7.
[0014] The front end portion of a rear arm 10 is supported by a rear portion of the body
frame 2 so as to be vertically swingable. A rear wheel 11 is arranged at the rear
end portion of the rear arm 10. A fuel tank 14 is arranged above the engine 3 in the
body frame 2, and a seat 15 is arranged on the rear side of the fuel tank 14.
[0015] The body frame 2 includes left and right frame members 2a, 2a, and upper and lower
cross members 20, 21 made of steel pipes that connect the rear end portions of the
left and right frame members 2a to each other.
[0016] The left and right frame members 2a are substantially laterally symmetrical. The
left and right frame members 2a include left and right upper tubes 16, 16, which have
tank rail portions 16a, 16a extending slightly downward to the rear from an upper
portion of the head pipe 6 and rear-arm supporting portions 16b, 16b extending rearwardly
downward from the rear ends of the tank rail portions 16a, and left and right down
tubes 17, 17, which have inclined portions 17a, 17a extending obliquely downward to
the rear from a lower portion of the head pipe 6 and horizontal portions 17b, 17b
extending substantially horizontally to the rear from the lower ends of the inclined
portions 17a.
[0017] Further, the left and right frame members 2a, 2a include left and right seat rails
18, 18 extending obliquely upward to the rear from the upper end portions of the left
and right rear-arm supporting portions 16b, and left and right seat stays 19, 19 that
connect between longitudinally midway portions of the seat rails 18 and lower portions
of the rear-arm supporting portions 16b.
[0018] The upper cross member 20 is arranged in each of the vertically halfway portions
of the left and right rear-arm supporting portions 16b, 16b.
[0019] The lower cross member 21 is arranged at the connecting portion between the lower
end portion of each of the left and right rear-arm supporting portions 16b, and the
rear end portion of each of the left and right horizontal portions 17b.
[0020] The engine 3 is a water-cooled four-cycle, parallel four-cylinder engine. The engine
3 is mounted with the cylinder axis tilted forward, and is suspended and supported
by the left and right upper tubes 16 and the left and right down tubes 17.
[0021] The engine 3 has a structure in which a cylinder block 27, a cylinder head 28, and
a head cover 29 are stacked in order on the upper mating surface of a crankcase 26
in which a crankshaft 25 is accommodated, a transmission case 26a in which a transmission
mechanism (not shown) is accommodated is integrally formed and connected to a rear
portion of the crankcase 26, and an oil sump 30 is connected to the bottom portion
of the crankcase 26.
[0022] Generally triangular rear-arm brackets 32, 32 are connected on the front side of
the left and right rear-arm supporting portions 16b so as to be positioned inside
the cradle. The rear arm 10 is supported by the left and right rear-arm supporting
brackets 32 via a pivot shaft 33.
[0023] On the rear side of the lower end portions of the left and right rear-arm supporting
portions 16b, footrests 34, 34 on which the rider places his/her feet are arranged
so as to project outward in the vehicle width direction.
[0024] The front end portions of generally triangular foot brackets 35, 35 that extend rearward
are connected to the left and right seat stays 19. A tandem footrest 36 on which the
passenger in the rear portion places his/her feet is arranged at the rear end portion
of each of the foot brackets 35.
[0025] A downwardly C-shaped stand bracket 37 that extends downward is connected to the
lower cross member 21. A main stand 38 is arranged in the stand bracket 37 so as to
be pivotable between an upright position in which the main stand 38 holds the vehicle
body, and a retracted position in which the main stand 38 is substantially in parallel
to the horizontal portions 17b of the down tubes 17.
[0026] The main stand 38 includes a stand body 38b having left and right leg portions 38a,
38a, and a footstep arm portion 38c formed so as to extend to the outside of the vehicle
from the leg portion 38a on the right side.
[0027] The intake system 4 includes four intake pipes 40 connected to a rear wall 28a of
the cylinder head 28 for respective cylinders, a throttle body 41 connected to each
intake pipe 40, and a common air cleaner connected to each throttle body 41.
[0028] A fuel injection valve 45 for injecting fuel to supply into an intake port (not shown)
formed in the cylinder head 28 is fitted to the downstream end portion of each of
the intake pipes 40.
[0029] The exhaust system 5 includes first to fourth exhaust pipes 50, 51, 52, 53, which
are connected to exhaust ports formed in a front wall 28b of the cylinder head 28
for respective cylinders and extend downward from the front wall 28b and then extends
rearward while passing below the engine 3, a right-side collecting portion (first
collecting portion) where the first and second exhaust pipes (first exhaust pipe group)
50, 51 are collected together, a left-side collecting portion (second collecting portion)
where the third and fourth exhaust pipes (second exhaust pipe group) 52, 53 are collected
together, a main collecting portion (third collecting portion) 56 where the left-side
and right-side collecting portions 54, 55 are collected together, and a single muffler
57 connected to a rearwardly extended portion 56b of the main collecting portion 56.
[0030] The first to fourth exhaust pipes 50 to 53, the right-side and left-side collecting
portions 54, 55, and the main collecting portion 56 are joined integrally by welding.
The muffler 57 is detachably connected to the rearwardly extended portion 56b of the
main collecting portion 56 by a band member 47.
[0031] Upstream-side catalysts (first catalyst) 48, 48 for performing purification of an
exhaust gas are arranged inside the right-side and left-side collecting portions 54,
55. A downstream-side catalyst (second catalyst) 49 for performing purification of
an exhaust gas is arranged inside the muffler 57.
[0032] The muffler 57 is arranged so as to be oriented obliquely upward on the left side
(other side) in the vehicle width direction of the rear wheel 11. As seen in plan
view, the muffler 57 has a cylindrical rear-side muffler portion 57b that extends
substantially in parallel to the vehicle body centerline C, and a substantially conical
front-side muffler portion 57c that extends from the front end of the rear-side muffler
portion 57b so as to be bent toward the vehicle body centerline C.
[0033] Further, as seen from the right side of the vehicle, most part of the muffler 57
is located within the projection plane of the rear wheel 11. The catalyst 49 is arranged
at the boundary between the front-side and rear-side muffler portions 57c, 57b.
[0034] A mounting strip 57a is formed in the upper wall of the rear-side muffler portion
57b of the muffler 57 so as to project upward. The mounting strip 57a is mounted and
fixed on the rear side of the tandem footrest 36 of the left foot bracket 35.
[0035] A flat mounting bracket 58 is connected to the right-side and left-side collecting
portions 54, 55 so as to bridge the upper ends of the respective collecting portions
54, 55. A mounting hole 58a is formed in the mounting bracket 58 so as to be positioned
between the two collecting portions 55, 54.
[0036] As shown in FIG. 9 that is a cross-sectional view of the right-side and left-side
collecting portions 54, 55 as seen from the rear of the vehicle, a grommet 59 is fitted
onto the mounting hole 58a. Further, a boss portion 30a is formed at the bottom portion
of the oil sump 30. The mounting bracket 58 is mounted to the boss portion 30a through
the intermediation of the grommet 59 by means of a bolt 60 that is inserted from below.
The right-side and left-side collecting portions 54, 55 are thus elastically supported
on the oil sump 30.
[0037] As shown in FIG. 10 that is a cross-sectional view of the main collecting portion
56 as seen from the rear of the vehicle, a mounting bracket 61 is connected to the
upstream-side end portion of the main collecting portion 56 so as to project upward.
Further, a pair of left and right boss portions 26b, 26b are formed at the bottom
portion of the transmission case 26a of the crankcase 26. A substantially T-shaped
stay 62 is fixed to the respective boss portions 26b by means of bolts 63, 63 that
are threadedly inserted from below. A cylinder member 62a is arranged in and fixed
to the stay 62 with its axis oriented in the vehicle width direction. A grommet 64
is inserted and fixed inside the cylinder member 62a.
[0038] The mounting bracket 61 is mounted to the stay 62 via the grommet 64 by means of
a bolt 65 inserted in the vehicle width direction. The main collecting portion 56
is thus elastically supported on the crankcase 26.
[0039] The right-side collecting portion 54 has a bifurcated connecting portion 54a to which
the first and second exhaust pipes 50, 51 are connected, a small-diameter portion
54b continuous to the connecting portion 54a and formed so as to have a smaller passage
area, and a large-diameter portion 54c continuous to the small-diameter portion 54b
and formed so as to have a larger passage area. The catalyst 48 is arranged in the
large-diameter portion 54c.
[0040] Like the right-side collecting portion 54, the left-side collecting portion 55 has
a bifurcated connecting portion 55a to which the third and fourth exhaust pipes 52,
53 are connected, a small-diameter portion 55b, and a large-diameter portion 55c.
The catalyst 48 is arranged in the large-diameter portion 55c.
[0041] As shown in FIGs. 3, 7, as seen in plan view, the right-side and left-side collecting
portions 54, 55 are displaced to the right side in the vehicle width direction with
respect to a vehicle body centerline C. That is, with the left-side and right-side
collecting portions 54, 55 seen as a single mass, its center is displaced to the right
side in the vehicle width direction. It should be noted that the centerline of the
engine 3 in the vehicle width direction coincides with the vehicle body centerline
C.
[0042] The connecting portion 54a of the right-side collecting portion 54 is displaced to
the right side in the vehicle width direction with respect to the vehicle body centerline
C and arranged in proximity to the right down tube 17. The small-diameter portion
54b is formed so as to be bent in a L shape to the left side in the vehicle width
direction from the connecting portion 54a. The downstream-side end portion of the
large-diameter portion 54c is in proximity to the vehicle body centerline C.
[0043] The connecting portion 55a of the left-side collecting portion 55 is arranged such
that its center substantially coincides with the vehicle body centerline C. The small-diameter
portion 55b is formed so as to be bent in a L shape to the left side in the vehicle
width direction on the vehicle body centerline C. The large-diameter portion 55c is
arranged with its inner end portion overlapping the vehicle body centerline C. In
other words, the large-diameter portions 54c, 55c of the right-side and left-side
collecting portions 54, 55 are displaced to the left side in the vehicle width direction
with respect to the connecting portions 54a, 55a.
[0044] As seen in plan view, the main collecting portion 56 is arranged so as to be positioned
on the left side in the vehicle width direction with respect to the vehicle body centerline
C. The main collecting portion 56 has a bifurcated connecting portion 56a to which
the right-side and left-side collecting portions 54, 55 are connected, and the rearwardly
extended portion (inclined portion) 56b. The rearwardly extended portion 56b extends
in a substantially linear fashion obliquely outward to the left from the connecting
portion 56a and, as seen from the lateral side, extends obliquely upward.
[0045] As shown in FIGs. 2, 3, the rearwardly extended portion 56b extends rearward so as
to pass through a space between the left-side footrest 34 and the main stand 38, from
a position in rear of the engine 3 and below the lower cross member 21. The muffler
57 is connected to the rear end portion of the rearwardly extended portion 56b.
[0046] The first to fourth exhaust pipes 50 to 53 has front-side exhaust pipe portions 50a
to 53a that extend obliquely downward from first to fourth exhaust ports in the front
wall 28b of the cylinder head 28 toward the right side (one side) in the vehicle width
direction, and rear-side exhaust pipe portions 50b to 53b that extend rearward from
the lower end portions of the front-side exhaust pipe portions 50a to 53a while being
bent so as to pass below the oil sump 30 of the engine 3. The detailed structure of
the first to fourth exhaust pipes 50 to 53 is as described below.
[0047] The right down tube 17 is positioned between the first and second exhaust pipes 50,
51, and the left down tube 17 is positioned between the third and fourth exhaust pipes
52, 53. The vehicle body centerline C is positioned at substantially the middle in
the vehicle width direction between the second and third exhaust pipes 51, 52.
[0048] As seen from the lateral side of the vehicle, the first to fourth front-side exhaust
pipe portions 50a to 53a are positioned forward of the inclined portions 17a of the
left and right down tubes 17, and crossing portions 17a' of the left and right inclined
portions 17a with the front-side exhaust pipe portions 50a to 53a have an elliptic
cross section crushed in the vehicle width direction (see FIG. 4). This prevents interference
from occurring as the inclined portions 17a, 17a of the down tubes 17 pass between
the respective front-side exhaust pipe portions 50a, 51a and 52a, 53a.
[0049] The first and second rear-side exhaust pipe portions 50b, 51b extend linearly to
the rear while in contact with each other from the lower end portions of the front-side
exhaust pipe portions 50a, 51a and are connected to the right-side collecting portion
54. Likewise, the third and fourth rear-side exhaust pipe portions 52b, 53b are connected
while in contact with each other to the left-side collecting portion 55.
[0050] As seen from the front, the first and second front-side exhaust pipe portions 50a,
51a first extend obliquely downward to the inner side toward the vehicle body centerline
C from the connecting portions with the exhaust ports, that is, from the upstream
end portions, and then extend obliquely downward while being bent to the outer side
at bending R portions r1, r2. The first and second front-side exhaust pipe portions
50a, 51a are thus generally shaped in a L shape as a whole.
[0051] The third and fourth front-side exhaust pipe portions 52a, 53a extend obliquely downward
from their upstream end portions toward the vehicle body centerline C while being
gently curved at bending R portions r3, r4. The lower end portion of the third front-side
exhaust pipe portion 52a extends to the right side in the vehicle width direction
beyond the vehicle body centerline C, and the lower end portion of the fourth front-side
exhaust pipe portion 53a extends so as to overlap the vehicle body centerline C.
[0052] As seen from the front of the vehicle, each of the bending R portions r1, r2, r3,
r4 has a center of curvature positioned on one side (right side) in the vehicle width
direction with respect to the center of each of the front-side exhaust pipes, and
is thus bent so as to be convex facing toward the other side in the vehicle width
direction. Further, the radii of the bending R's of the bending R portions r1, r2
of the first and second front-side exhaust pipe portions 50a, 51a are set to values
smaller than the radii of the bending R' s of the bending R portions r3, r4 of the
third and fourth front-side exhaust pipe portions 52a, 53a (see Figs. 4, 5).
[0053] Furthermore, top portions c3, c4 of the bending R's of the bending R portions r3,
r4 of the third and fourth front-side exhaust pipe portions 52a, 53a are positioned
higher than top portions c1, c2 of the bending R' s of the bending R portions r1,
r2 of the first and second front-side exhaust pipe portions 50a, 51a.
[0054] As seen in a cross-section taken transversely of the vehicle width direction, the
upstream-side portion (line VIIIa-VIIIa in FIG. 4) and downstream-side portion (line
VIIIb-VIIIb in FIG. 4) of each of the first to fourth front-side exhaust pipe portions
50a to 53a with respect to the bending R portions r1 to r4 have the following structure.
[0055] As shown in FIG. 8, the centers a1 to a4 of the first to fourth front-side exhaust
pipe portions 50a to 53a in the upstream-side portion are arranged so as to diverge
toward the front of the vehicle as a whole. In other words, a curve w1 connecting
the centers a1 to a4 is convex facing toward the rear of the vehicle. Further, the
centers b1 to b4 of the first to fourth front-side exhaust pipe portions 50a to 53a
in the downstream-side portion are arranged so as to converge toward the front of
the vehicle as a whole. In other words, a curve w2 connecting the centers b1 to b4
is convex facing toward the front of the vehicle. Stated in still other words, in
the upstream-side portion from the bending R portion, the second and third front-side
exhaust pipe portions 51a, 52a are positioned on the rear side with respect to the
first and fourth front-side exhaust pipe portions 50a, 53a, and in the downstream-side
portion, the second and third front-side exhaust pipe portions 51a, 52a are positioned
on the front side with respect to the first and fourth front-side exhaust pipe portions
50a, 53a.
[0056] As seen from the front of the vehicle, rearwardly bent portions 50a', 51a' at the
lower ends of the first and second front-side exhaust pipe portions 50a, 51a are formed
on the outer side in the vehicle width direction with respect to, and positioned higher
than, rearwardly bent portions 52a', 53a' at the lower ends of the third and fourth
front-side exhaust pipe portions 52a, 53a. Further, the rearwardly bent portion 50a'
of the first front-side exhaust pipe portion 50a is formed so as to be positioned
higher than the rearwardly bent portion 51a' of the second front-side exhaust pipe
portion 51a (see FIG. 4).
[0057] Accordingly, as seen from the lateral side of the vehicle, the first and second rear-side
exhaust pipe portions 50b, 51b are arranged at positions higher than the third and
fourth rear-side exhaust pipe portions 52b, 53b, and further the first rear-side exhaust
pipe portion 50b is arranged at a position higher than the second rear-side exhaust
pipe portion 51b. The bank angle becomes large as a result.
[0058] The exhaust system 5 includes an exhaust valve 67. The exhaust valve 67 is arranged
at the downstream-side end portion of the rearwardly extended portion 56b of the main
collecting portion 56 and on the upstream side of the downstream-side catalyst 49,
and is formed by arranging a valve plate 67b, which causes the passage area inside
the main collecting portion 56 to change, on a valve shaft 67a that radially extends
through the main collecting portion 56 (see FIG. 7). The valve shaft 67a is arranged
in a titled manner so that its position is higher on the outer side in the vehicle
width direction. A drive cable (not shown) is connected to the valve shaft 67a.
[0059] The exhaust system 5 has an oxygen concentration sensor 68 that detects the concentration
of oxygen in an exhaust gas. An air fuel ratio is found on the basis of the oxygen
concentration detected by the oxygen concentration sensor 68, and the amount of fuel
supply from the fuel injection valve 45 is controlled so that this air-fuel ratio
becomes a target air-fuel ratio.
[0060] The oxygen concentration sensor 68 has a detecting portion 68a inserted with its
distal end portion positioned inside the rearwardly extended portion 56b of the main
collecting portion 56, a sensor body 68b connected to the detecting portion 68a, and
an external connection cable 68c for leading a detection signal to the outside from
the detecting portion 68a (see FIG. 11).
[0061] A sensor fitting hole 56d is formed in the rearwardly extended portion 56b of the
main collecting portion 56. A nut member 69 is connected to the fitting hole 56d in
an airtight manner. The oxygen concentration sensor 68 is detachably mounted to the
main collecting portion 56 by fastening and fixing the sensor body 68b to the nut
member 69 in an airtight manner.
[0062] The oxygen concentration sensor 68 is arranged in an upper wall portion 56e of the
rearwardly extended portion 56b of the main collecting portion 56, and on the upstream
side in front of the exhaust valve 67. The oxygen concentration sensor 68 thus detects
the concentration of oxygen in the exhaust gas that has passed through each of the
left and right upstream-side catalysts 48, 48.
[0063] The oxygen concentration sensor 68 is arranged in a tilted manner so that the upper
portion of the sensor body 68b is positioned on the inner side in the vehicle width
direction and upward. Further, as seen in the longitudinal direction of the vehicle,
the oxygen concentration sensor 68 is arranged so as to cross the exhaust valve 67.
[0064] As seen from the lateral side of the vehicle, the oxygen concentration sensor 68
is arranged between the engine 3 and the rear wheel 11, and so as to be positioned
substantially at the same height as the lower cross member 21.
[0065] Further, the oxygen concentration sensor 68 is arranged so as to be positioned above
the main stand 38 that is in the retracted position, positioned below the rear arm
10 and on its outer side in the vehicle width direction, and positioned on the inner
side in the vehicle width direction of the footrest 34 on the left side.
[0066] Accordingly, as seen from the lateral side, the oxygen concentration sensor 68 is
surrounded by the lower cross member 21, the stand bracket 37, the stand body 38b,
the footstep arm portion 38c, the rear-arm supporting portion 16b, and the rear arm
10.
[0067] According to this embodiment, the four exhaust pipes, the first to fourth exhaust
pipes 50 to 53 connected to the exhaust ports of the respective cylinders in the front
wall 28b of the cylinder head 28 are extended from the rear wall 28b obliquely downward
to the right side in the vehicle width direction and are connected to the right-side
and left-side collecting portions 54, 55 that are displaced to this right side, and
the right-side and left-side collecting portions 54, 55 are connected via the main
collecting portion 56 to the single muffler 57 that is displaced to the left side
in the vehicle width direction. Therefore, when the exhaust system is seen as a whole,
the first to fourth exhaust pipes 50 to 53 and the left-side and right-side collecting
portions 54, 55 are positioned on the right side in the vehicle width direction, and
the muffler 57 is positioned on the left side in the vehicle width direction, with
respect to the vehicle body centerline C. The exhaust pipes and the muffler, which
are heavy-weight objects in the exhaust system 5, can be thus laid out with good balance
on the left and right, thereby achieving good weight balance with respect to the vehicle
width direction.
[0068] In this embodiment, the first to fourth exhaust pipes 50 to 53 are tilted obliquely
downward toward the right side from the front wall 28b. Therefore, the exhaust pipes
are enlarged in length as compared with a case where, for example, the exhaust pipes
are extended vertically downward, thereby making it possible to secure a required
exhaust pipe length and an improvement in output performance.
[0069] In this embodiment, when seen as a whole, the first to four exhaust pipes 50 to 53
are first displaced toward the right side and connected to the right-side and left-side
collecting portions 54, 55 arranged so as to be displaced to this right side, and
are then connected via the main collecting portion 56 to the muffler 57 arranged so
as to be displaced to the opposite side (left side). This gives an element of flow
and motion to the design of the exhaust system when seen as a whole, thereby making
it possible to achieve enhanced marketability in appearance. It should be noted that
when it is said that the left and right collecting portions 54, 55 are arranged so
as to be displaced to one side in the vehicle width direction, this means that when
the collecting portions 54, 55 are seen as a single mass, its center is displaced
to one side in the vehicle width direction.
[0070] In this embodiment, since the radii of the bending R's of the bending R portions
r1, r2 in the vehicle width direction of the first and second front-side exhaust pipe
portions 50a, 51a are set smaller than the radii of the bending R's of the bending
R portions r3, r4 in the vehicle width direction of the third and fourth front-side
exhaust pipe portions 52a, 53a, the exhaust pipe lengths of the respective exhaust
pipes 50 to 53 can be made substantially same. That is, since the first and second
exhaust pipes 50, 51 have a generally curved shape, and the third and fourth exhaust
pipes 52, 53 have a generally linear shape, it is possible to reduce the difference
in exhaust pipe length between the first and second exhaust pipes 50, 51 and the third
and fourth exhaust pipes 52, 53.
[0071] Further, since the radius of the bending R differs between the bending R portions
r1, r2 of the first and second exhaust pipes 50, 51 and the bending R portions r3,
r4 of the third and fourth exhaust pipes 52, 53, the feel of a smooth curve with little
or no linear section, that is, a hand-bent or hand-made feel can be given. Enhanced
marketability in appearance can be achieved also in this respect.
[0072] In this embodiment, the curve w1 in the upstream-side portions of the first to fourth
exhaust pipes 50 to 53 with respect to the bending R portions r1 to r4 is formed in
a convex shape facing toward the rear of the vehicle, and the curve w2 in the downstream-side
portions is formed in a convex shape facing toward the front of the vehicle. The above-mentioned
hand-bent feel can be given also in this respect.
[0073] In this embodiment, since the rearwardly bent portions 50a' , 51a' of the first and
second exhaust pipes 50, 51 are positioned higher than the rearwardly bent portions
52a' , 53a' of the third and fourth exhaust pipes 52, 53, it is possible to secure
the bank angle when arranging the respective exhaust pipes 50 to 53 so as to be displaced
to the right side in the vehicle width direction, thereby achieving increased maneuverability.
[0074] In this embodiment, the right-side and left-side collecting portions 54, 55 are supported
by the oil sump 30 via the mounting bracket 58, thereby achieving increased reliability
in terms of the supporting strength for the right-side and left-side collecting portions
54, 55 that are heavy-weight objects.
[0075] In this embodiment, the front end portion of the main collecting portion 56 is supported
by the transmission case 26a of the crankcase 26 via the mounting bracket 61, thereby
achieving increased reliability in terms of the supporting strength for the main collecting
portion 56 that is a heavy-weight object.
[0076] Further, the portions on the front side and rear side of the catalysts 48 arranged
in the left-side and right-side collecting portions 54, 55 are supported by the engine
3 via the mounting brackets 58, 61, respectively, thereby achieving a further increase
in reliability in terms of supporting strength.
[0077] While in the above embodiment the description is directed to the case where the number
of exhaust pipes is four, the exhaust system according to the present invention is
also applicable to a case where the number of exhaust pipes is three or five. In this
case as well, the same effect as that of the above embodiment can be obtained by arranging
the exhaust pipes so as to be displaced to one side in the vehicle width direction.
DESCRIPTION OF REFERENCE NUMERALS AND SYMBOLS
[0078]
12: motorcycle
2: body frame
3: engine
5: exhuast system
28: cylinder head
28b: front wall
26: crankcase
30: oil sump
48, 49: upstream-side/downstream-side catalyst (first/second catalyst)
50, 51: first/second exhaust pipe (first exhaust pipe group)
52, 53: second/third exhaust pipe (second exhaust pipe group)
54, 55: right-side/left-side collecting portion (first/second collecting portion)
56: main collecting portion (third collecting portion)
57: muffler
a1 to a4: center of cross-section taken along vehicle width direction on upstream
side
b1 to b4: center of cross-section taken along vehicle width direction on upstream
side
C: vehicle body centerline
c1 to c4: top portion of bending R portion
r1 to r4: bending R portion
r1' to r4': radius of bending R of bending R portion
w1, w2: curve
1. A motorcycle (1) comprising a body frame (2), an engine (3) mounted to the body frame,
and an exhaust system connected to the engine,
wherein:
the exhaust system includes a plurality of exhaust pipes (50 , 51, 52, 53) connected
to a front wall of the engine (3) and extending rearward while passing below the engine,
a collecting portion or portions (54, 55) where the plurality of exhaust pipes are
collected together, and a muffler (57) connected to the collecting portion;
as seen from the front of the vehicle, the plurality of exhaust pipes (50, 51, 52,
53) extend from the front wall of the engine rearward towards a first side of a centre
line (c) extending along the length of the motorcycle (11) in a vehicle width direction
of the vehicle and so as to pass below the engine, and are connected to the collecting
portion (s) (54, 54), and the muffler (57) is arranged on a second opposing side of
a centre line extending along the length of the motorcycle (1) in the width direction
of the vehicle and connected to the collecting portion(s), characterized in that the motorcycle has
the centre of mass of the collecting portion(s) (54, 55) when considered as a single
mass is located on said first side of said motorcycle (1) with respect to said centre
line (c) and the centre of mass of said muffler (57) is located on said second opposing
side of the motorcycle with respect to said centre line (c).
2. The motorcycle according to Claim 1, wherein the plurality of exhaust pipes extend
obliquely downward toward one side in the vehicle width direction.
3. The motorcycle according to Claim 1 or Claim 2, wherein as seen from the front of
the vehicle, the exhaust pipes each have a bending R portion having a convex shape
facing toward the other side in the vehicle width direction.
4. The motorcycle according to Claim 3, wherein of the plurality of exhaust pipes, a
top portion of the bending R portion of an exhaust pipe connected to the other side
portion of the front wall of the engine is positioned higher than a top portion of
the bending R portion of an exhaust pipe connected to one side portion.
5. The motorcycle according to Claim 3 or Claim 4, wherein centers of cross-sections
taken along the vehicle width direction of the plurality of exhaust pipes on an upstream
side of the bending R portion are configured to diverge toward the front of the vehicle.
6. The motorcycle according to Claim 5, wherein a curve connecting the centers of the
cross-sections taken along the vehicle width direction of the plurality of exhaust
pipes on the upstream side of the bending R portion is convex facing toward the rear
of the vehicle.
7. The motorcycle according to Claim 3, wherein centers of cross-sections taken along
the vehicle width direction of the plurality of exhaust pipes on a downstream side
of the bending R portion are configured to converge toward the front of the vehicle.
8. The motorcycle according to Claim 7, wherein a curve connecting the centers of the
cross-sections taken along the vehicle width direction of the plurality of exhaust
pipes on the downstream side of the bending R portion forms a convex shape facing
toward the front of the vehicle.
9. The motorcycle according to Claim 1, wherein the plurality of exhaust pipes (50, 51,
52, 53) each have a rearwardly bent portion that is bent rearward, and as seen from
the front of the vehicle (1), of the plurality of exhaust pipes, the rearwardly bent
portion of an exhaust pipe connected to one side in the vehicle width direction of
the front wall of the engine is positioned higher than the rearwardly bent portion
of an exhaust pipe connected to the other side in the vehicle width direction of the
front wall of the engine (3).
10. The motorcycle according to Claim 1, wherein the collecting portion is supported on
a bottom portion of the engine.
11. The motorcycle according to Claim 10, further comprising an oil sump (30) arranged
at the bottom portion of the engine, wherein the collecting portion is supported on
the oil sump.
12. The motorcycle according to Claim 1, wherein a first catalyst is arranged in the collecting
portion.
13. The motorcycle according to Claim 1, wherein a second catalyst is arranged in the
muffler.
14. The motorcycle according to Claim 1,
wherein:
the plurality of exhaust pipes include a first exhaust pipe group connected to one
side portion of the front wall of the engine, and a second exhaust pipe group connected
to the other side portion;
the collecting portion includes a first collecting portion for collecting the first
exhaust pipe group together, a second collecting portion for collecting the second
exhaust pipe group together, and a third main collecting portion for collecting the
first collecting portion and the second collecting portion together; and
the muffler is connected to the third main collecting portion.
1. Ein Motorrad (1), das einen Karosserierahmen (2), einen Motor (3), der an dem Karosserierahmen
befestigt ist und ein Auspuffsystem aufweist, das mit dem Motor verbunden ist, wobei:
das Auspuffsystem eine Mehrzahl von Auspuffrohren (50, 51, 52, 53), die mit einer
Vorderwand des Motors (3) verbunden sind und sich rückwärts erstrecken während sie
unter dem Motor verlaufen, einen Sammelabschnitt oder mehrere Abschnitte (54, 55),
wo die Mehrzahl der Auspuffrohre gesammelt sind, und einen Schalldämpfer (57), der
mit dem Sammelabschnitt verbunden ist umfasst;
betrachtet von der Vorderseite des Fahrzeugs erstreckt sich die Mehrzahl der Auspuffrohre
(50, 51, 52, 53) von der Vorderwand des Motors rückwärts hin zu einer ersten Seite
einer Mittellinie (c), die sich entlang der Länge des Motorrads (11) in einer Fahrzeugbreitenrichtung
des Fahrzeugs erstreckt, um unter dem Motor zu verlaufen, und sind mit dem (den) Sammelabschnitt(en)
(54, 54) verbunden, und der Schalldämpfer (57) ist auf einer zweiten gegenüberliegenden
Seite einer Mittellinie angeordnet, die sich entlang der Länge des Motorrads (1) in
der Breitenrichtung des Fahrzeugs erstreckt und ist mit dem einen oder den mehreren
Sammelabschnitten verbunden, dadurch gekennzeichnet, dass
das Motorrad den Masseschwerpunkt des (der) Sammelabschnitts(e) (54, 55), wenn es
als einzelne Masse betrachtet wird, auf der ersten Seite des Motorrads (1) im Hinblick
auf die Mittellinie (c) aufweist und der Masseschwerpunkt des Schalldämpfers (57)
auf der zweiten, gegenüberliegenden Seite des Motors im Hinblick auf die Mittellinie
(c) angeordnet ist.
2. Das Motorrad gemäß Anspruch 1, bei dem sich die Mehrzahl der Auspuffrohre schräg abwärts
hin zu einer Seite in der Fahrzeugbreitenrichtung erstreckt.
3. Das Motorrad gemäß Anspruch 1 oder Anspruch 2, bei dem, betrachtet von der Vorderseite
des Fahrzeugs, die Auspuffrohre jeweils einen Biegungs-R-Abschnitt aufweisen, mit
einer konvexen Form, der hin zu der anderen Seite in der Fahrzeugbreitenrichtung gewandt
ist.
4. Das Motorrad gemäß Anspruch 3, bei dem von der Mehrzahl der Auspuffrohre ein oberer
Abschnitt des Biegungs-R-Abschnitts eines Auspuffrohres, der mit dem anderen Seitenabschnitt
der Vorderwand des Motors verbunden ist, höher positioniert ist als ein oberer Abschnitt
des Biegungs-R-Abschnitts eines Auspuffrohrs, der mit einem Seitenabschnitt verbunden
ist.
5. Das Motorrad gemäß Anspruch 3 oder Anspruch 4, bei dem Mitten der Querschnitte genommen
entlang der Fahrzeugbreitenrichtung der Mehrzahl der Auspuffrohre auf einer Seite
in Verarbeitungsrichtung aufwärts von dem Biegungs-R-Abschnitt konfiguriert sind,
um hin zu der Vorderseite des Fahrzeugs zu divergieren.
6. Das Motorrad gemäß Anspruch 5, bei dem eine Kurve, die die Mitten der Querschnitte
verbindet, genommen entlang der Fahrzeugbreitenrichtung der Mehrzahl der Auspuffrohre
auf der Seite in Verarbeitungsrichtung aufwärts von dem Biegungs-R-Abschnitt, konvex
ist und hin zu der Rückseite des Fahrzeugs gewandt ist.
7. Das Motorrad gemäß Anspruch 3, bei dem Mitten der Querschnitte genommen entlang der
Fahrzeugbreitenrichtung der Mehrzahl der Auspuffrohre auf einer Seite in Verarbeitungsrichtung
abwärts von dem Biegungs-R-Abschnitt konfiguriert sind, um hin zu der Vorderseite
des Fahrzeugs zu konvergieren.
8. Das Motorrad gemäß Anspruch 7, bei dem eine Kurve, die die Mitten der Querschnitte
verbindet, genommen entlang der Fahrzeugbreitenrichtung der Mehrzahl der Auspuffrohre
auf der Seite in Verarbeitungsrichtung abwärts von dem Biegungs-R-Abschnitt, eine
konvexe Form bildet, die hin zu der Vorderseite des Fahrzeugs gewandt ist.
9. Das Motorrad gemäß Anspruch 1, bei dem die Mehrzahl der Auspuffrohre (50, 51, 52,
53) jeweils einen rückwärts gebogenen Abschnitt aufweist, der rückwärts gebogen ist,
und betrachtet von der Vorderseite des Fahrzeugs (1) von der Mehrzahl der Auspuffrohre,
der rückwärts gebogene Abschnitt eines Auspuffrohrs, verbunden mit einer Seite in
der Fahrzeugbreitenrichtung der Vorderwand des Motors, höher positioniert ist als
der rückwärts gebogene Abschnitt eines Auspuffrohrs, verbunden mit der anderen Seite
in der Fahrzeugbreitenrichtung der Vorderwand des Motors (3).
10. Das Motorrad gemäß Anspruch 1, bei dem der Sammelabschnitt auf einem Bodenabschnitt
des Motors getragen ist.
11. Das Motorrad gemäß Anspruch 10, das ferner eine Ölwanne (30) aufweist, die an dem
Bodenabschnitt des Motors angeordnet ist, wobei der Sammelabschnitt auf der Ölwanne
getragen ist.
12. Das Motorrad gemäß Anspruch 1, bei dem ein erster Katalysator in dem Sammelabschnitt
angeordnet ist.
13. Das Motorrad gemäß Anspruch 1, bei dem ein zweiter Katalysator in dem Schalldämpfer
angeordnet ist.
14. Das Motorrad gemäß Anspruch 1, bei dem:
die Mehrzahl der Auspuffrohre eine erste Auspuffrohrgruppe aufweist, die mit einem
Seitenabschnitt der Vorderwand des Motors verbunden ist, und eine zweite Auspuffrohrgruppe,
die mit dem anderen Seitenabschnitt verbunden ist;
wobei der Sammelabschnitt einen ersten Sammelabschnitt zum Sammeln der ersten Auspuffrohrgruppe
miteinander, einen zweiten Sammelabschnitt zum Sammeln der zweiten Auspuffrohrgruppe
miteinander und einen dritten Hauptsammelabschnitt zum Sammeln des ersten Sammelabschnitts
und des zweiten Sammelabschnitts miteinander umfasst; und
der Schalldämpfer mit dem dritten Hauptsammelabschnitt verbunden ist.
1. Motocyclette (1) comprenant un châssis de corps (2), un moteur (3) monté sur le châssis
de corps, et un système d'échappement connecté au moteur,
dans lequel:
le système d'échappement comporte une pluralité de tuyaux d'échappement (50, 51, 52,
53) connectés à une paroi avant du moteur (3) et s'étendant vers l'arrière, tout en
passant au-dessous du moteur, une ou des parties de raccordement (54, 55), où la pluralité
de tuyaux d'échappement sont raccordés l'un à l'autre, et un silencieux (57) connecté
à la partie de raccordement;
vus depuis l'avant du véhicule, la pluralité de tuyaux d'échappement (50, 51, 52,
53) s'étendent de la paroi avant du moteur vers l'arrière vers un premier côté d'une
ligne de centre (c) s'étendant le sur la longueur de la motocyclette (11) dans le
sens de la largeur du véhicule et de manière à passer au-dessous du moteur, et sont
connectés à la ou aux parties de raccordement (54, 54), et le silencieux (57) est
disposé sur un deuxième côté opposé d'une ligne de centre s'étendant sur la longueur
de la motocyclette (1) dans le sens de la largeur du véhicule et est connecté à la
ou aux parties de raccordement,
caractérisée par le fait que le centre de masse de la ou des parties de raccordement (54, 55), lorsqu'elles sont
considérées comme étant une seule masse, se situe dudit premier côté de ladite motocyclette
(1) par rapport à ladite ligne de centre (c) et que le centre de masse dudit silencieux
(57) se situe dudit deuxième côté opposé de la motocyclette par rapport à ladite ligne
de centre (c).
2. Motocyclette selon la revendication 1, dans laquelle la pluralité de tuyaux d'échappement
s'étendent obliquement vers le bas vers un côté dans le sens de la largeur du véhicule.
3. Motocyclette selon la revendication 1 ou la revendication 2, dans laquelle, vus de
l'avant du véhicule, les tuyaux d'échappement présentent, chacune, une partie courbée
R ayant une forme convexe orientée vers l'autre côté dans le sens de la largeur du
véhicule.
4. Motocyclette selon la revendication 3, dans laquelle, de la pluralité de tuyaux d'échappement,
une partie supérieure de la partie courbée R d'un tuyau d'échappement connecté à l'autre
partie latérale de la paroi avant du moteur est positionnée plus haute qu'une partie
supérieure de la partie courbée R d'un tuyau d'échappement connecté à l'une partie
latérale.
5. Motocyclette selon la revendication 3 ou la revendication 4, dans laquelle les centres
des sections, prises dans le sens de la largeur du véhicule, de la pluralité de tuyaux
d'échappement d'un côté amont de la partie courbée R sont configurés de manière à
diverger vers l'avant du véhicule.
6. Motocyclette selon la revendication 5, dans laquelle une courbe connectant les centres
des sections, prises dans le sens de la largeur du véhicule, de la pluralité de tuyaux
d'échappement du côté amont de la partie courbée R est convexe, orientée vers l'arrière
du véhicule.
7. Motocyclette selon la revendication 3, dans laquelle les centres des sections, prises
dans le sens de la largeur du véhicule, de la pluralité de tuyaux d'échappement d'un
côté aval de la partie courbée R sont configurés de manière à converger vers l'avant
du véhicule.
8. Motocyclette selon la revendication 7, dans laquelle une courbe connectant les centres
des sections, prises dans le sens de la largeur du véhicule, de la pluralité de tuyaux
d'échappement du côté aval de la partie courbée R forme une forme convexe orientée
vers l'avant du véhicule.
9. Motocyclette selon la revendication 1, dans laquelle la pluralité de tuyaux d'échappement
(50, 51, 52, 53) présentent, chacun, une partie courbée vers l'arrière qui est courbée
vers l'arrière et, vu de l'avant du véhicule (1), de la pluralité de tuyaux d'échappement,
la partie courbée vers l'arrière d'un tuyau d'échappement connecté à un côté, dans
le sens de la largeur du véhicule, de la paroi avant du moteur est positionnée plus
haute que la partie courbée vers l'arrière d'un tuyau d'échappement connecté à l'autre
côté, dans le sens de la largeur du véhicule, de la paroi avant du moteur (3).
10. Motocyclette selon la revendication 1, dans laquelle la partie de raccordement est
supportée sur une partie inférieure du moteur.
11. Motocyclette selon la revendication 10, comprenant par ailleurs un carter à huile
(30) disposé dans la partie inférieure du moteur,
dans laquelle la partie de raccordement est supportée sur le carter à huile.
12. Motocyclette selon la revendication 1, dans laquelle un premier catalyseur est disposé
dans la partie de raccordement.
13. Motocyclette selon la revendication 1, dans laquelle un deuxième catalyseur est disposé
dans le silencieux.
14. Motocyclette selon la revendication 1,
dans laquelle:
la pluralité de tuyaux d'échappement comportent un premier groupe de tuyaux d'échappement
connectés à une partie latérale de la paroi avant du moteur, et un deuxième groupe
de tuyaux d'échappement connectés à l'autre partie latérale;
la partie de raccordement comporte une première partie de raccordement destinée à
raccorder le premier groupe de tuyaux d'échappement entre eux, une deuxième partie
de raccordement destinée à raccorder le deuxième groupe de tuyau d'échappement entre
eux, et une troisième partie de raccordement principale destinée à raccorder la première
partie de raccordement et la deuxième partie de raccordement l'une à l'autre; et
le silencieux est connecté à la troisième partie de raccordement principale.